With the increase in cost of fossil fuels, many developments have been made to reduce window heat loss. A particularly useful resource book covering the subject is "MOVABLE INSULATION--A Guide to Reducing Heating and Cooling Losses Through the Windows in Your Home," by William K. Langdon, Rodale Press, 1980. A second resource is "THERMAL SHUTTERS AND SHADES--Over 100 Schemes for Reducing Heat-Loss Through Windows," by William A. Shurcliff, Brick House Publishing Co., Inc., 1980.
A wide variety of movable insulation is disclosed in these books. The various shades have differing insulating effects and differing costs. The fabric of this invention provides a relatively low-cost means of greatly increasing the insulative factor for a home window. For comparison, a single-pane window tested by Architectural Testing, Inc., of York, Pa., in accordance with standards published in ASTM C-236 has an R factor of approximately 1.30. Adouble-pane insulated window with a 3/8-inch (0.95 cm) air space has an R factor of about 1.83. Windows having outside storm windows have an R factor of approximately 2.20. A window insulated with rolling shades constructed with the fabric of this invention has an insulating factor of about 7.69. Thus the insulated fabric of this invention is more effective than additional glazing and is less expensive, especially for retrofitting.